LIGAND/RECEPTOR INTERACTIONS IN THE TGF BETA SUPERFAMILY

描述：转化生长因子β（TGF-β）是一种多功能 细胞因子，其控制细胞外基质的关键成分的产生。 基质和功能作为一个有效的生长抑制剂的上皮和内皮细胞 通过对细胞周期起负面作用来影响细胞。TGF-β信号传导是由 两种单程跨膜受体，称为TGF-β I型和TGF-β II型， II受体和一个细胞内效应子家族，称为SMADS。 该系统中的信号传导由异源四聚体 由生长因子配体和两个拷贝组成的信号传导复合物 I型和II型受体。目前，完全缺乏 关于受体本身和细节的结构信息 它们与这类重要的生长因子之间的联系。相当大 理解促进增长的相互作用有实际的好处 由于TGF-β信号传导受到严格控制， 通过过度表达TGF-β或突变破坏这种平衡 天然存在于受体或SMAD蛋白中的蛋白质已经被证明， 与许多病理生理状态有关，包括纤维化 疾病和癌症。此外，TGF-β及其信号受体是 高度保守的生长因子和生长因子大家族的原型 因子受体，称为TGF-β超家族。这些因素中有许多起着 在发育和细胞内稳态中起关键作用，但目前 关于分子决定因素的信息很少， 控制配体-受体特异性。这项建议的主要目的是 使用直接的基于结构的方法来提供明确的信息 关于氨基酸序列和空间决定因素， 异源四聚体中的配体-受体和受体-受体相互作用 TGF-β信号复合物。在实验上，这一目标将得以实现。 通过使用溶液NMR技术来a）解析配体的结构， 两种受体类型的结合结构域和B）描绘决定簇 控制受体-配体和受体-受体结合的特异性。 Hinck博士计划用于这些研究的模型系统是分离的 人TGF-β I型和II型受体的配体结合结构域。 多核溶液核磁共振技术非常适合研究这一点 由于I型可溶性受体的相对小的尺寸而引起的问题 11.1 kDa，Ⅱ型14.1kDa，最近开发的E. coli表达系统。 实现这一目标的初步实验工作将侧重于 可溶性II型受体及其结合位点鉴定。期间 在项目的最后阶段，Hinck博士计划解决 可溶性I型受体，并研究其与II型受体的相互作用 受体和TGF-β。受体组装的一般原理 从这些研究将a）提供一个框架，开始预测 TGF-β超家族的配体-受体特异性和B）将使 一种合理的方法来干预TGF-β信号通路。

DESCRIPTION: Transforming growth factor beta (TGF-beta) is a multifunctional cytokine which controls the production of key components of the extracellular matrix and functions as a potent growth inhibitor of epithelial and endothelial cells by acting negatively on the cell cycle. TGF-beta signaling is mediated by two single pass transmembrane receptors, known as the TGF-beta type I and type II receptors, and a family of intracellular effectors, known as SMADS. Signaling in this system is initiated by assembly of a heterotetrameric signaling complex consisting of growth factor ligand and two copies each of the type I and type II receptors. At present, there is a complete lack of structural information regarding both the receptors themselves and the details of their association with this important class of growth factors. Considerable practical benefits exist in understanding the interactions which mediate growth factor-receptor assembly since TGF-beta signaling is tightly controlled, and disruption of this balance through overexpression of TGF-beta or mutations which occur naturally within the receptors or SMAD proteins has been shown to be linked to a number of pathophysiological states, including fibrotic disorders and cancer. Additionally, TGF-beta and its signaling receptors are the prototype for a large family of highly conserved growth factors and growth factor receptors, known as the TGF-beta superfamily. Many of these factors play critical roles in development and in cellular homeostasis, yet at present little information is available regarding the molecular determinants which govern ligand-receptor specificity. The primary objective of this proposal is to use a direct structure-based approach to provide definitive information regarding amino acid sequence and spatial determinants which govern ligand-receptor and receptor-receptor interactions in the heterotetrameric TGF-beta signaling complex. Experimentally, this objective will be accomplished by using solution NMR techniques to a) solve the structures of the ligand binding domains of the two receptor types and b) to delineate the determinants of specificity which govern receptor-ligand and receptor-receptor association. The model system that Dr. Hinck plans to use for these studies is the isolated ligand binding domains of the human TGF-beta type I and type II receptors. Multinuclear solution NMR techniques are ideally suited for studying this problem owing to the relatively small size of the soluble receptors, type I 11.1 kDa, type II 14.1 kDa, and recently developed E. coli expression systems. Initial experimental efforts at achieving this objective will focus on the soluble type II receptor and identification of its binding site. During the final period of the project, Dr. Hinck plans to solve the solution structure of the soluble type I receptor and to investigate its interaction with the type II receptor and TGF-beta. The general principles of receptor assembly which emerge from these studies will a) provide a framework for beginning to predict ligand-receptor specificity across the TGF-beta superfamily and b) will enable a rational approach toward intervening in the TGF-beta signaling pathway.